In how many ways can be bowler take four wickets in a single 6 balls over?

There are 5 red and 6 black balls in a bag. In how many ways 6 balls can be selected if there are at least 2 balls of each colour?

In how many ways can we arrange 6 different flowers in a circle ? In how many ways we can form a garland using these flowers ?

In how many ways can 5 balls be placed in 4 tins of any number of balls can be placed in any tin ?

A box contains two white balls, three black balls and four red balls. In how many ways can three balls be drawn from the box if at least one black ball is to be included in a draw ?

A box contains 5 different red and 6 different white balls.In how many ways can 6 balls be selected so that there are atleast 2 balls of each colour?